Devices for coating wires and in particular for enamelling electric wires



1968 R. A. GOYFFON 09 DEVICES FOR COATING WIRES AND IN PARTICULAR FORENAMELLING ELECTRIC WIRES Filed Dec. 21, 1966 4 Sheets-Sheet l Nov. 26,1968 R. A. GOYFFON 3,412,709

DEVICES FOR COATING WIRES AND IN PARTICULAR FOR ENAMELLING ELECTRICWIRES Filed Dec. 21, 1966 4 Sheets-Sheet 2 3 E JZ 39 35 (13 J39] g d Ell, 16 3 1 1 l$l H 3] I Il 1 1 V 14 3 iy Nov. 26, 1968 R. A. GOYFFONDEVICES FOR COATING WIRES AND IN PARTICULAR FOR ENAMELLING ELECTRICWIRES Filed Dec.

4 Sheets-Sheet 5 R. A. GOYFFON DEVICES FOR COATING WIRES AND INPARTICULAR FOR ENAMELLING ELECTRIC WIRES Nov. 26, 1968 4 Shets-Sheet 4Filed Dec. 21, 1966 United States Patent 3,412,709 DEVICES FOR COATINGWIRES AND IN PARTIC- ULAR FOR ENAMELLING ELECTRIC WIRES Roland A.Goytfon, Macon, France, assignor to Manufacture de Fils Isoles Taurus(Mafit), Macon, France, a society of France Filed Dec. 21, 1966, Ser.No. 603,512 Claims priority, application France, Jan. 7, 1966, 45,190 8Claims. (Cl. 118-405) ABSTRACT OF THE DISCLOSURE Wires 1 to be enamelledare passed through an apparatus including a body 12 provided, on the onehand, with a tank 13 through which enamel under pressure is made tocirculate continuously and, on the other hand, with housings 16 intendedto accommodate die-blocks 17 provided with notches 31 for the passage ofthe wires therethrough, said body 12 being further provided with achamber 14 containing felt elements 15. The die blocks 17 arepositioned, against the action of springs 16 by a cover 18. Enamel flowscontinuously through tank 13. The wires 1 to be enamelled passtransversely to tank 13 and to chamber 14 through grooves 21, 22, 23provided in said body 12. The enamel lea-ks are collected through agroove 35. The cross section of the die block notches 31 is U-shaped,the lower cross section of the U being semi-circular and of a diameterjust a little greater than that of the wire, the height of the -U beingsubstantially equal to said first mentioned diameter.

The present invention relates to devices for coating wires with asuitable substance and in particular for enamelling electric wires.

The object of the invention is to provide an improved devices of thiskind and in particular to permit of increasing the speed of enamellingwhile avoiding too great an evaporation of the enamelling bath.

The essential feature of this invention consists in making use of dieblocks movably mounted in an apparatus fed with coating liquid andconsisting of cylindrical elements engaged in corresponding housings ofsaid apparatus.

Other features of the present invention will become apparent during thedetailed description of two embodiments thereof.

Preferred embodiments of the present invention will be hereinafterdescribed with reference to the appended drawing given merely by way ofexample, in which:

FIG. 1 diagrammatically shows a plant for enamelling electric wiresaccording to the present invention;

FIG. 2 is a perspective view of the enamel coating device according tothe present invention, the cover plate of this device being showndetached from the body thereof;

FIG. 3 is a cross sectional view of the device of FIG. 2, the lid beingfitted in position;

FIG. 4 is a detail view, showing on an enlarged scale and in verticalsection one of the die blocks of the device;

FIG. 5 is an elevational view, partly in section, of a device madeaccording to a second embodiment of the invention;

FIG. 6 is an end view corresponding to FIG. 5;

FIG. 7 is a plane view, with parts cut away, corresponding to FIGS. 5and 6, and

FIG. 8 shows the cover plate of the device of FIGS. 5 to 7, seen fromunder.

It should be reminded that there exist several types of devices forcoating wires with a liquid, and in particular electric wires withenamel.

3,412,709 Patented Nov. 26, 1968 Some of these devices make use ofroller dies consisting of steel cylinders provided with grooves oftriangular cross section for calibrating the enamel or varnish liquidwith which the wires are to be coated. Other devices make use of feltelements.

The devices making use of roller dies have some drawbacks, due inparticular to the necessity of driving said roller dies in rotation andto the d-ifiiculties which result therefrom, in particular for adjustingthe roller dies or for replacing them. Furthermore, the triangular shapeof the goove cross sections leads to a quick wear and tear thereof dueto the action of the spring necessary for maintaining the wire at thebottom of the groove.

The devices where the wire is passed between two felt elementsimpregnated with varnish, also involves serious drawbacks. In particularthey do not permit a sufficient accuracy. It is true thatthere aredevices of this kind with a channel provided in the felt elements forthe passage of the wire, enamel being fed to this channel from a pumphaving a controlled output. Such devices constitute an improvement tothe current practice but they can be used only with limited outputsbecause there is no return of enamel from the above mentioned channel.It follows that the rates of enamelling remain low and furthermore thereare risks of rises of temperature involving losses by evaporation.

The various prior systems have in common the drawback that they permitonly relatively low rates 'of enamelling.

According to the present invention, the wire coating device comprisesstationary die blociks having calibrated notches, preferably U-shaped,for the outflow of the coating liquid around the wires, said blocksbeing mounted removable so that they can be changed very easily, saiddevice being fed in a continuous manner with the coating liquid througha chamber which is closed (with the exception of the passages for theinlet and outlet of the wires), the outflow through said passagesreturning to the liquid feed means, whereby there is no risk ofelevation of the temperature and therefore enamelling can be performedat high rates.

Furthermore the U-shaped section permits of limiting leaks and obtaininglayers of enamel or varnish of very great accuracy, even when they arevery thin.

Furthermore, as the layers of varnish or enamel are very thin it ispossible to increase the speed of the wire, that is to say the rate ofenamelling, since polymerization of such thin layer can be obtained veryquickly in ovens provided for this purpose. For the obtainment of thicklayers, it suffices'to pass the wire through the device in successiveoperations separated from one another by a passage through the oven, thenumber of these operations being variable according to the desiredthickness of coating.

Embodiments of devices according to the present invention will now bedescribed.

FIG. 1 shows an enamelling plant which comprises: at A a device forapplying the enamel through which wires 1, corresponding to severalsuccessive steps of the enamelling operation, are pulled by pullingmeans 60, enamel or varnish arriving at 2 into the apparatus and leavingit at 3,

at B a constant level tank heated by a water bath at 11, fed with enamelor varnish at 4 and receiving solvent from conduit 5 (for instanceleading to return conduit 3), in such manner that the viscosity remainsconstant, this solvent arriving for instance from a circuit 6 past anelectrovalve 7 controlled by viscosimeter 8,

at C a circulation pump,

at 9 a filter, and

at a pressure gauge to measure and maintain a given pressure of enamelor varnish in device A.

In the embodiment illustrated by FIGS. 2 to 4 the device for applyingthe enamel or varnish comprises felt elements and die blocks, the wirepassing successively through these two means.

In this embodiment, the coating device A comprises the followingelements:

On the one hand, a die block carrying body 12 of elongatedparallelepipedal shape containing a longitudinal tank .13 forming achannel for circulation of enamel under pressure, a longitudinal recess14 for felt elements 15 and housings 16 for receiving the die blocks 17,and

On the other hand, a cover plate 18 adapted to fit on the upper face ofsaid body 1 so as to close the recesses thereof and to leave only inletand outlet passages for wires 1.

Body 12 and cover plate 18 are in contact with each other throughfluidtight plane surfaces, but there is provided in cover plate 18, tocomplete the recesses of body 12 and to permit the passage of the Wires,recesses 19 and 20- located opposite tank .13 and recess 14.

Grooves are provided in body 12 at 21, 22, 23 for the passage of thewires and above grooves 22 and 23 the cover plate is also provided withgrooves 24 and 25 adapted to cooperate with notches 22 and 23,respectively. The felt elements 15 are housed in recesses 14 and 20.

Housings 16 and die blocks 17 are of cylindrical shape and springs 26are interposed between the bottoms of housings 16 and the die blocks topush said die blocks against the cover plate 18. Said cover plate 18 issecured to body 12 by screws such as 27.

As illustrated by FIG. 4, die blocks 17 have a perfectly plane upperface 28 against which is to be applied the under face 29 of cover plate18, which is also perfectly plane. In the top portion of every die block17 there is provided a channel 30 provided with a notch 31 for thepassage of the wire, said notch being in the form of a U, the lowerportion of said notch 31 being of semicylindrical shape, with a diameterequal to the sum of the diameter of the wire 1 passing therethrough andof the thickness of the layer of enamel to be formed on said wire, theupper ortion of notch 31 being limited by two straight surfaces at adistance from each other equal to the notch lower portion diameter andthe total height of the notch being equal to said last mentioneddiameter.

This U-shaped section is the most favorable one for reducing to aminimum the amount of enamel permitted to leak out and for inserting thewires to be enamelled into the die blocks.

FIG. 2 shows that, cover plate 18 being lifted and die blocks 17 beingin po ition, it is very easy to insert the wires to be coated withenamel or varnish, after which cover plate 18 is lowered and fixed onbody 12.

Die blocks 17 are provided with positioning pins 32 adapted to engage invertical slots 33 of body 12, whereby channels 30 are correctlypositioned with respect to grooves 21. The bottom of housings 12 isclosed by a plate 34 which is removable to permit access to saidhousings (FIG. 3).

In order to recuperate the enamel that has leaked out from grooves 21and 23, there is provided, around body 12, a collecting gutter 35through which said enamel is returned to the general circuit.

Enamel arrives through a conduit 36 leading to tank 13, whereas theoutflow of said enamel takes place freely through a passage 37, channel38 and an outlet conduit 39. It is therefore possible at any time, byadjustment of pump C or through any other suitable means, to have intank 13 a given pressure indicated by pressure gauge 10 (FIG. l). Inorder to adjust this pressure as exactly as possible, an air separator40 (FIG. 1) may be provided.

This pressure being determined, it controls accurately the amount ofenamel carried along by the wire 1 passing through the notch 31 of every.die block.

During operation, every wire 1 enters through a groove 23, passesbetween felt elements 15 impregnated with enamel, is coated with enamelin tank 13 and passes out through notch 31, the amount of enameladhering to said wire being accurately calibrated. The wire then passesthrough a polymerization oven and, if necessary, comes back to thedevice for another coating operation to pass through the next die block,of suitable size, and

so on.

It is therefore possible to obtain a final coating of any desiredthickness. Of course, by varying the pressure in tank 13, it is possibleto modify this thickness.

Such a device complies with all the required conditions, to wit:

possibility of easily replacing the die blocks,

high resistance of these die blocks to wear and tear,

easy insertion of the wires in their .die blocks, when the cover plateis removed,

possibility of coating the wire, on every operation,

with a small amount of enamel, which facilitates polymerization andtherefore permits of increasing the speed of passage of the wires,

possibility, owing to the fact that the device comprises means forreturning the liquid to the feed circuit, of avoiding any heating of theenamel, and therefore any evaporation,

possibility of working with a liquidtight device, which thereforecontributes in preventing evaporation, and possibility of easilycontrolling the delivery of enamel,

in particular by acting upon the pressure.

By Way of indication, for wires of a diameter of 8/ mm. it is possibleto reach wire passage speeds of 600 meters per minute with enamelcoating thickness averaging 10/ 1000 mm. and a number of successiveoperations averaging nine, the pressure in the device being for instanceof 4 cms. of mercury above atmospheric pressure. An increase of thispressure above 4 cms. would permit of increasing the mean thickness ofthe coating from one to two microns.

The speed of 600 meters per minute, which is much higher than thatgenerally used, is not at all a limit speed. It corresponds to theobtainment of an excellent wire when some factors are imposed, forinstance the temperature of the polymerization oven.

In the embodiment illustrated by FIGS. 5 to 8 there are no felt elementsto oppose enamel leakage at the inlets of the wires. But two sets of dieblocks are provided, respectively at 17 and 17 The tank of FIGS. 2 to 4is in this case replaced by feed channels 41, 42 provided in the coverplate and disposed above the die blocks.

The circulation of liquid enamel takes place in the following manner.

The inflow of the liquid takes place through a feed conduit 43communicating through a vertical passage 46 with channel 42. The liquidflows through grooves 22 into channel 41 leading through verticalpassage 47 to return channel 44. Grooves 22 serve both to the passage ofthe wires therethrough and to the flow of the liquid from channel 42 tochannel 41. In each of these grooves 22 the wire is therefore located ina stream of liquid flowing in the same direction as said wire istravelling. This is very important for very fine wires (of a diameterlower than 8/ 100 mm.) which can withstand only low pulling stresses.The inlet die blocks 17 serve merely to limit the outflow of liquid buttheir resistance to the travel of the wire is lower than in systemsmaking use of felt pieces. The outlet die block 17 is, on the contrary,a calibrating die block. Channel 42 may have, as shown, by FIG. 5 across section decreasing from the left toward the right so as tocompensate for the decrease of volume of the liquid in circulation, thusmaintaining a constant pressure (and therefore a constant flow rate) ineach of the grooves 22. On the contrary, the cross section of channel 41is increasing from the left to the right. A conduit 45 evacuates theamounts of liquid that have leaked out into gutter 35. Conduit 45 is incommunication with the collecting gutter through a hollow bolt 48, 49communicating with a passage 50 provided in an angle of body 12.

Of course, the invention applies to the case where die blocks would beprovided for the passage of the wires upstream of felt elements.

The U-shaped notches might be used in the case of movable die blocks.

In a general manner, while the above description discloses what aredeemed to be practical and efficient embodiments of the presentinvention, said invention is not limited thereto as there might bechanges made in the arrangement, disposition and form of the partswithout departing from the principle of the invention as comprehendedwithin the scope of the appended claims.

What I claim is:

1. A wire coating device which comprises, in combination:

a body, including a fluidtig-ht cover, forming at least one channel forthe continuous flow therethrough, in a given direction, of a coatingsubstance in the liquid state, said body having opposed walls extendingin said direction, said walls being provided with respective wirepassages locate opposite each other,

means for pulling a wire to be coated with said liquid substance throughsaid passages across said channel transversely to the direction of flowof said subtance, so that said wire enters said body through one of saidpassages, called inlet passage, and leaves said channel through theother of said passages, called outlet passage,

means for opposing outflow of said coating liquid through said inletpassage,

a piece carried by the wall of said body containing said outlet passage,said piece being provided with a U- shaped notch forming said outletpassage, the bottom portion of said notch being of semi-circular crosssection of a diameter equal to the sum of the diameter of said wire andof the desired thickness of said liquid coating and the top portion ofsaid notch being of a cross section limited by two parallel straightlines, tangent to the ends of said semi-circular cross section, whereasthe depth of said U-shaped notch is equal to the diameter of thesemi-circular bottom portion thereof, the top of said U-shaped notchbeing closed by said cover.

2. A wire coating device which comprises, in combination,

a body, including a fluidtight cover, forming at least one channel forthe continuous flow therethrough in a given direction of a coatingsubstance in the liquid state, said body having opposed walls extendingin said direction, said walls being provided with respective wirepassages located opposite each other,

means for pulling a wire to be coated with said liquid substance throughsaid passages across said channel transversely to the direction of flowof said substance, so that said wire enters said body through one ofsaid passages, called inlet passage, and leaves said body through theother of said passages, called outlet passage,

means for opposing outflow of said coating liquid through said inletpassage,

the wall of said body containing said outlet passages having an upperedge co-operating with the inner face of said cover, said last mentionedwall being provided with a cylindrical housing transverse to thedirection of said wire and opening into said upper edge,

a cylindrical block removably mounted in said housing and slidable insaid housing, said cylindrical block having a flat end face portionadapted to fit in a fluidtight manner against a corresponding flat innerface portion of said cover,

spring means in said housing urging said cylindrical block against saidcover inner face,

said cylindrical block being provided at its top, ad-

jacent to said cover inner face portion, with a notch forming saidoutlet passage, whereby said cover closes the upper side of said outletpassage.

3. A device according to claim 2 wherein said notch is U-shaped thebottom portion of said U-shaped notch being of semi-circular crosssection of a diameter equal to the sum of the diameter of said wire andof the desired thickness of said liquid coating and the top portion ofsaid notch being of a cross section limited by two parallel straightlines tangent to the ends of said semi-circular cross section, whereas,the depth of said U-shaped notch is equal to the diameter of thesemi-circular bottom portion thereof.

4. A device according to claim 3 including means for constantly placingthe liquid in said tank under pressure.

5. A device according to claim 3 wherein the means for opposing outflowof the coating liquid through said inlet passages consist of feltelements located on opposite sides of the wire and held tightly againstsaid wire, said felt elements being housed in said body on the otherside of said inlet passage from said tank.

6. A device according to claim 3 wherein the means for opposing outflowof the coating liquid through said inlet passages consist of acylindrical block slidable in a cylindrical housing of the wall of saidbody containing said inlet passages, said last mentioned block beingresiliently urged against the inner face of said cover, said lastmentioned cylindrical block being provided, at the end thereof where itis applied against said cover inner face, with a U-shaped notch thebottom portion of which is, in a direction transverse to said wire, ofsemi-circular cross section of a diameter substantially equal to thediameter of said wire and the top portion of which is of a cross sectionlimited by two straight lines tangent to the ends of said semi-circularcross section, whereas the depth of said last mentioned U-shaped notchis equal to the diameter of the semi-circular bottom portion thereof.

7. A device according to claim 6 wherein there are two channels for theflow of said coating substance, said channels being provided in theinner face of said cover, said body being provided with groovesextending between said channels and serving for the passage of the wireand also to the flow of the liquid coating substance from one of saidchannels to the other.

8. A device according to claim 7 wherein that of said two channels whichcommunicates directly with said outlet passages is of decreasing crosssection from the inlet end thereof, whereas that of said two channelswhich communicates directly with said inlet passages is of increasingcross section from the inlet end thereof.

References Cited UNITED STATES PATENTS 1,049,170 12/1912 Thomas 118-4052,007,441 7/1935 Candy 118-405 X 2,280,415 4/ 1942 Larmuth 118 CHARLESA. WILLMUTH, Primary Examiner.

I. MCINTOSH, Assistant Examiner.

